title: Structural similarities in the active-site region between potato and rabbit muscle phosphorylases: a lysyl residue located close to the pyridoxal 5'-phosphate.
abstract: P1,P2-bis(5'-pyridoxal)diphosphate crosslinks between the original cofactor (pyridoxal 5'-phosphate) linking residue and Lys-573 in rabbit muscle phosphorylase (Shimomura, S., Nakano, K., & Fukui, T. (1978) Biochem. Biophys. Res. Commun. 82, 462-468). We have applied the same technique to potato phosphorylase to compare the structures of the active-site regions of the two enzymes, which have different regulatory properties. The reagent was bound to the potato enzyme in the same binding mode as the rabbit muscle enzyme. A sequence study on the potato enzyme labeled with this reagent revealed that it crosslinks between the original cofactor-linking lysyl residue and another lysyl residue, respectively corresponding to Lys-679 and Lys-573 in the rabbit muscle enzyme, and that the sequence Lys-573 to Leu-577 in the rabbit muscle enzyme is conserved in the potato enzyme. These findings indicate structural similarities in the active-site region between the phosphorylases, and suggest the importance of a lysyl residue in the catalytic mechanism of the phosphorylase reaction.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D008239:Lysine; D009132:Muscles / Q000201:enzymology*; D006005:Phosphorylases / Q000378:metabolism*; D010944:Plants / Q000201:enzymology*; D011732:Pyridoxal Phosphate; D011817:Rabbits; D013045:Species Specificity
chemical_list: D011732:Pyridoxal Phosphate; D006005:Phosphorylases; D008239:Lysine